K. Lindgren

Photon-induced nuclear reactions above 1 GeV: (I). Experimental

Abstract The yields of the reactions 12 C(γ, n ) 11 C , 27 Al (γ, π + ) 27 Mg , 27 Al (γ, 2 pn ) 24 Na , 127 I (γ,y p χ n ) and 197 Au (γ,χ n ) have been measured in the energy range 1–7 GeV by the activation method without chemical separation. The yields and the F/B ratios in the photo-fission of Au and Pb have been measured by glass-plate detectors. From the yields the cross sections have been deduced. Further, the mass distribution from 238U photofission was measured. The results fit well to earlier measurements below 1 GeV. The analysis and discussion of the spallation and fission results are given in a series of consecutive papers.

Photofission in bismuth at intermediate energy

Abstract The yields of 43 fission products from photofission in 209 Bi induced by 600 MeV bremsstrahlung have been measured. From these values the mass and charge distributions have been determined. The peak position of the mass distribution is at A p = 96.3 ± 0.5a.m.u. and the FWHM is 34.8 ± 0.7a.m.u. The ranges of 15 fission products have been determined using the thick-target thick-catcher technique and the kinetic energies have been deduced. Experimental results are compared with cascade-evaporation calculations in combination with liquid drop model calculations for the fission process.

Photofission in gold at intermediate energy

Abstract Using the thick-target thick-catcher technique the yields of 29 fission products from photofission in 197 Au induced by 600 MeV bremsstrahlung have been measured. From these values, mass and charge distributions have been determined. The experimental results are compared with cascade-evaporation calculations in combination with calculations based on the liquid drop model.

Pion effects in 127I(γ, xn) reactions of high multiplicity

Abstract The yields of the reactions (γ, 6n), (γ, 7n), (γ, 8n) and (γ, 9n) in 127 I have been measured by activation analysis from their thresholds up to 900 MeV. The experimental mean cross sections above the pion threshold have been compared to theoretical calculations based upon a cascade-evaporation model and good agreement is found.

The 16O(γ, n)15O∗ and 16O(γ, p)15N∗ reactions at intermediate energies

Abstract The yields of the reactions 16 O(γ, n 15 O ∗ and 16 O(γ, p) 15 N ∗ have been measured as a function of maximum bremsstrahlung energy from 100 to 800 MeV in an in-beam experiment. The de-excitation γ-radiation from the first 3 2 − excited states in 15 O and 15 N was measured with a large Ge(Li) detector. Analysis of the yield curves shows that in this energy region only very few of the nucleons in the upper nuclear shells contribute to the cross section.

Photonuclear reactions in 45Sc and natCu induced by 2 GeV bremsstrahlung

Abstract Yields and isomeric yield ratios of nuclei produced in the irradiation of 45 Sc and nat Cu with bremsstrahlung of E γ max = 2 GeV have been measured by the activation method. The experimental yields are compared to predictions with a Rudstam formula modified to photonuclear reactions.

Pion photoproduction on197Au to ground and isomeric states in197Hg

The cross sections for the photoproduction ofπ− on197Au leading to the 1/2− ground and 13/2+ isomeric states in197Hg have been measured from threshold to 750 MeV by use of the activation method. A suitable chemical separation technique was developed and applied in this experiment. The individual cross sections and the isomeric ratio are compared to calculations based on the impulse approximation.

Photonucleon reactions in 40Ca at intermediate energies

Abstract The yields of the reactions 40 Ca(γ, n) 39 Ca ∗ and 40 Ca(γ, p) 39 K ∗ to the first three excited states have been measured for bremsstrahlung with end-point energies in the region 100–750 MeV. Upper limits for the C 2 S values for the first excited state were deduced from the pion photoproduction contribution to the measured yields.

The (γ, 2n) reaction in 12c and 16o at intermediate energies

Abstract The yields of the reactions 12 C(γ, 2n) 10 C and 16 O(γ, 2n) 14 O have been measured as a function of maximum bremsstrahlung energy from about 100 to 800 MeV by the activation method. The cross sections are deduced and compared with cascade-evaporation calculations, cross sections for the (γ, n) reaction and results from particle induced reactions.

The reaction 11B(γ, p)10Be∗ at intermediate energies

Abstract The yield of the reaction 11 B(γ, p) 10 Be ∗ has been measured for bremsstrahlung end-point energies between 100 and 800 MeV by observing de-excitation γ-rays from the first excited state. The number of nucleons available for the reaction is determined and compared to theoretical predictions for proton pick-up on 11 B.